Wonderstone Sandstone Coasters with etched Wisconsin Scenes - Explore SetThese are the coasters that really work! Sandstone created 180 million years ago by wind and water and colored by iron oxides. It has not been changed in anyway except cut into pieces for coasters. Every coaster is different -- and an original work of art from Mother Nature. These unique coasters are extremely porous, absorbing all condensation. When a glass is lifted, these natural sandstone coasters will not stick. Has a cork base to protect your table. This "Explore" set of four coasters has beautiful Wisconsin scenes etched into the stone and includes: one Lighthouse scene, one Hot Air Ballon scene, one Barn scene, and one Windmill scene. Also see our Outdoor set. Wooden holder is sold separately Quantity @ $20.95 each